Researchers demonstrate direction-dependent vibrational strong coupling at the nanoscale
Researchers from the Quantum Nano-Optics group at the University of Oviedo and the Center for Research on Nanomaterials and Nanotechnology (CINN-CSIC), in collaboration with the 2D Nanophotonics group at the Donostia International Physics Center (DIPC) and the Nanooptics group at CIC nanoGUNE, have observed, for the first time, vibrational strong coupling (VSC) between hyperbolic phonon polaritons in MoO₃ slabs and molecular vibrations of organic compounds.
VSC arises when molecular vibrations interact strongly with electromagnetic modes, forming hybrid light–matter states. This effect underpins polariton chemistry, where such hybrid states can alter chemical reactivity.
In MoO₃, VSC is directional because hyperbolic phonon polaritons exhibit orientation-dependent wavelength and confinement. The results, published in Nature Photonics, may open new routes for directional polariton chemistry and the development of ultrasensitive molecular sensors.